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linux-next/samples/bpf/bpf_helpers.h

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samples: bpf: elf_bpf file loader simple .o parser and loader using BPF syscall. .o is a standard ELF generated by LLVM backend It parses elf file compiled by llvm .c->.o - parses 'maps' section and creates maps via BPF syscall - parses 'license' section and passes it to syscall - parses elf relocations for BPF maps and adjusts BPF_LD_IMM64 insns by storing map_fd into insn->imm and marking such insns as BPF_PSEUDO_MAP_FD - loads eBPF programs via BPF syscall One ELF file can contain multiple BPF programs. int load_bpf_file(char *path); populates prog_fd[] and map_fd[] with FDs received from bpf syscall bpf_helpers.h - helper functions available to eBPF programs written in C Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-02 07:06:37 +08:00
#ifndef __BPF_HELPERS_H
#define __BPF_HELPERS_H
/* helper macro to place programs, maps, license in
* different sections in elf_bpf file. Section names
* are interpreted by elf_bpf loader
*/
#define SEC(NAME) __attribute__((section(NAME), used))
/* helper functions called from eBPF programs written in C */
static void *(*bpf_map_lookup_elem)(void *map, void *key) =
(void *) BPF_FUNC_map_lookup_elem;
static int (*bpf_map_update_elem)(void *map, void *key, void *value,
unsigned long long flags) =
(void *) BPF_FUNC_map_update_elem;
static int (*bpf_map_delete_elem)(void *map, void *key) =
(void *) BPF_FUNC_map_delete_elem;
samples/bpf: Add simple non-portable kprobe filter example tracex1_kern.c - C program compiled into BPF. It attaches to kprobe:netif_receive_skb() When skb->dev->name == "lo", it prints sample debug message into trace_pipe via bpf_trace_printk() helper function. tracex1_user.c - corresponding user space component that: - loads BPF program via bpf() syscall - opens kprobes:netif_receive_skb event via perf_event_open() syscall - attaches the program to event via ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); - prints from trace_pipe Note, this BPF program is non-portable. It must be recompiled with current kernel headers. kprobe is not a stable ABI and BPF+kprobe scripts may no longer be meaningful when kernel internals change. No matter in what way the kernel changes, neither the kprobe, nor the BPF program can ever crash or corrupt the kernel, assuming the kprobes, perf and BPF subsystem has no bugs. The verifier will detect that the program is using bpf_trace_printk() and the kernel will print 'this is a DEBUG kernel' warning banner, which means that bpf_trace_printk() should be used for debugging of the BPF program only. Usage: $ sudo tracex1 ping-19826 [000] d.s2 63103.382648: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63103.382684: : skb ffff880466b1d300 len 84 ping-19826 [000] d.s2 63104.382533: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63104.382594: : skb ffff880466b1d300 len 84 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1427312966-8434-7-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-26 03:49:23 +08:00
static int (*bpf_probe_read)(void *dst, int size, void *unsafe_ptr) =
(void *) BPF_FUNC_probe_read;
static unsigned long long (*bpf_ktime_get_ns)(void) =
(void *) BPF_FUNC_ktime_get_ns;
static int (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
(void *) BPF_FUNC_trace_printk;
samples/bpf: bpf_tail_call example for tracing kprobe example that demonstrates how future seccomp programs may look like. It attaches to seccomp_phase1() function and tail-calls other BPF programs depending on syscall number. Existing optimized classic BPF seccomp programs generated by Chrome look like: if (sd.nr < 121) { if (sd.nr < 57) { if (sd.nr < 22) { if (sd.nr < 7) { if (sd.nr < 4) { if (sd.nr < 1) { check sys_read } else { if (sd.nr < 3) { check sys_write and sys_open } else { check sys_close } } } else { } else { } else { } else { } else { } the future seccomp using native eBPF may look like: bpf_tail_call(&sd, &syscall_jmp_table, sd.nr); which is simpler, faster and leaves more room for per-syscall checks. Usage: $ sudo ./tracex5 <...>-366 [001] d... 4.870033: : read(fd=1, buf=00007f6d5bebf000, size=771) <...>-369 [003] d... 4.870066: : mmap <...>-369 [003] d... 4.870077: : syscall=110 (one of get/set uid/pid/gid) <...>-369 [003] d... 4.870089: : syscall=107 (one of get/set uid/pid/gid) sh-369 [000] d... 4.891740: : read(fd=0, buf=00000000023d1000, size=512) sh-369 [000] d... 4.891747: : write(fd=1, buf=00000000023d3000, size=512) sh-369 [000] d... 4.891747: : read(fd=1, buf=00000000023d3000, size=512) Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-20 07:59:05 +08:00
static void (*bpf_tail_call)(void *ctx, void *map, int index) =
(void *) BPF_FUNC_tail_call;
samples: bpf: elf_bpf file loader simple .o parser and loader using BPF syscall. .o is a standard ELF generated by LLVM backend It parses elf file compiled by llvm .c->.o - parses 'maps' section and creates maps via BPF syscall - parses 'license' section and passes it to syscall - parses elf relocations for BPF maps and adjusts BPF_LD_IMM64 insns by storing map_fd into insn->imm and marking such insns as BPF_PSEUDO_MAP_FD - loads eBPF programs via BPF syscall One ELF file can contain multiple BPF programs. int load_bpf_file(char *path); populates prog_fd[] and map_fd[] with FDs received from bpf syscall bpf_helpers.h - helper functions available to eBPF programs written in C Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-02 07:06:37 +08:00
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions
*/
struct sk_buff;
unsigned long long load_byte(void *skb,
unsigned long long off) asm("llvm.bpf.load.byte");
unsigned long long load_half(void *skb,
unsigned long long off) asm("llvm.bpf.load.half");
unsigned long long load_word(void *skb,
unsigned long long off) asm("llvm.bpf.load.word");
/* a helper structure used by eBPF C program
* to describe map attributes to elf_bpf loader
*/
struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
};
tc: bpf: add checksum helpers Commit 608cd71a9c7c ("tc: bpf: generalize pedit action") has added the possibility to mangle packet data to BPF programs in the tc pipeline. This patch adds two helpers bpf_l3_csum_replace() and bpf_l4_csum_replace() for fixing up the protocol checksums after the packet mangling. It also adds 'flags' argument to bpf_skb_store_bytes() helper to avoid unnecessary checksum recomputations when BPF programs adjusting l3/l4 checksums and documents all three helpers in uapi header. Moreover, a sample program is added to show how BPF programs can make use of the mangle and csum helpers. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-02 08:12:13 +08:00
static int (*bpf_skb_store_bytes)(void *ctx, int off, void *from, int len, int flags) =
(void *) BPF_FUNC_skb_store_bytes;
static int (*bpf_l3_csum_replace)(void *ctx, int off, int from, int to, int flags) =
(void *) BPF_FUNC_l3_csum_replace;
static int (*bpf_l4_csum_replace)(void *ctx, int off, int from, int to, int flags) =
(void *) BPF_FUNC_l4_csum_replace;
samples: bpf: elf_bpf file loader simple .o parser and loader using BPF syscall. .o is a standard ELF generated by LLVM backend It parses elf file compiled by llvm .c->.o - parses 'maps' section and creates maps via BPF syscall - parses 'license' section and passes it to syscall - parses elf relocations for BPF maps and adjusts BPF_LD_IMM64 insns by storing map_fd into insn->imm and marking such insns as BPF_PSEUDO_MAP_FD - loads eBPF programs via BPF syscall One ELF file can contain multiple BPF programs. int load_bpf_file(char *path); populates prog_fd[] and map_fd[] with FDs received from bpf syscall bpf_helpers.h - helper functions available to eBPF programs written in C Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-02 07:06:37 +08:00
#endif
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